Printing cylinder



y 17, 4- E. w. HAWARD El AL- 1,966,858

PRINTING CYLINDER Filed Aug. 26, 1933 Inventors 50% E j Attorn y- Patented July 17, 1934 UNITED STATES PRINTING CYLINDER Ernest William Haward, Camberwell, and Alfred Tyrrell Hopkins, Orpington, Kent, England, assignors to Haward Gravure Machine Company, Limited, London, England Application August 26, 1933, Serial No. 686,916 In Great Britain January 19, 1932 7 Claims.

The invention relates to printing or plate cylinders of intaglio printing machines and particularly to cylinders that are adapted to carry metallic or like printing plates secured in a gap,

and has among its objects to prevent splashing of the printing ink when the gap cover of the printing or plate cylinder passes beneath the doctor blade, and to prevent damage to or distortion of the blade by reason of irregularities along the lines of junction between the gap cover and the edges of the gap of the printing or plate cylinder.

According to the invention the longitudinal edges of the gap cover and of the printing or plate cylinder at the gap are relatively so disposed that, in the direction of rotation of the printing or plate cylinder, a longitudinal ridge or shoulder is formed to the rear of each line of junction between the gap cover and the printing or plate cylinder rising above the level of the surface forward of the line of junction and adapted to bear against the underside of the 'doctor blade in such manner as to lift the edge of the blade out of contact with the surface or to relieve the pressure thereon as the blade passes over the line of junction. This may be effected by causing the longitudinal edge of the gap cover at the first line of junction between the gap cover and the cylinder to be disposed above the normal surface level of the cylinder, the surface of the gap cover thence sloping downwardly slightly below the normal surface of the cylinder and towards the end of the gap curving upwardly to join the normal surface of the cylinder at the second line of junction between the gap cover and cylinder, the edge of the cylinder at the junction line being adapted to bear against the underside of the doctor blade. Alternatively a ridge may be formed at the first line of junction by providing the surface of the cylinder adjacent the edge of the gap depressed slightly in the radial direction to form a shallow recess into which the edge of the doctor blade may pass as the adjacent edge of the gap cover bears upon the underside of the blade. At the second line of junction the ridge may be formed by slight longitudinal elevation of the surface of the cylinder at the edge of the gap. In the travel of the doctor blade across the junction between the cylinder and the gap cover pressure is gently applied to the underside of the doctor blade by the ridge formed to lift the edge of the blade over the line of junction which pressure is removed as the blade travels across the gap cover and is then applied again at the line of junction between the gap cover and the cylinder, thus ensuring passage of the doctor blade across the gap without risk of splashing. The invention is diagrammatically illustrated by way of example in the accompanying drawing which is a diagrammatic end View of a printing or plate cylinder provided with a gap cover according to the invention; it will be understood that the size and curvilinear form of the gap cover relative to the printing or plate cylinder as been considerably exaggerated so as more clearly to illustrate the invention.

In the accompanying drawing Figures 1 and 2 illustrate diagrammatically two constructions of rinting or plate cylinder and gap plate or cover according to the invention, in end elevation.

In carrying the invention into effect according to the construction represented in Figure 1 of the drawing a printing or plate cylinder a is provided with a gap plate or cover I).

At the first line of junction between the printing or plate cylinder (1 and the gap plate or cover I) the gap plate or cover is formed with a ridge 0 which extends longitudinally along the edge of the cover. The surface of the gap plate or cover I) thence slopes downwardly slightly below the normal surface of the cylinder, and towards the end of the gap curves upwardly to join the normal surface of the cylinder at the second line of junction where the longitudinal edge of the cylinder gap forms a ridge (1. It will be understood that the form of the middle part of the plate or cover is relatively unimportant provided it does not project beyond the normal peripheral surface of the cylinder, and provided ridges areformed at the lines of junction.

In operation, in the travel of the doctor blade 2 across the gap cover, at the first line of junction between the printing or plate cylinder a and the gap cover 1) pressure is gently applied by the ridge 0 against the under surface of the doctor blade e at a position immediately to the rear of the front edge of the doctor blade whereby it is lifted across the line of junction without making contact with it. The doctor blade passes across the second line of junction with its under surface in contact with the ridge d.

Thus theedge of the doctor blade is maintained out of contact with the surface or the pressure thereon is relieved or lightened at both the lines of junction between the cylinder and gap plate or cover in the travel of the blade across the gap. In the modified construction represented in Figure 2 the edge a of the cylinder a forward of the first line of junction with the gap plate b is depressed in a slight degree, while the edge a of the cylinder to the rear of the second line of junction is elevated to a slight degree.

In carrying the invention into effect, it has been found that a height of ridge of one sixty-fourth of an inch is suitable for a printing or plate cylinder of a diameter of 10 inches but these dimensions may range from two thousandths of an inch or less to one eighth of an inch or more as may be required to meet practical requirements such as the diameter of the printing or plate cylinder and the width of the gap, and the disposition of the blade and its flexibility.

It will be understood that the angle of the doctor blade to the normal surface of the cyl inder is for normal operation slightly greater than tangential.

It will be understood furthermore that the form of the ridges and of the adjoining sur faces of the gap cover and the cylinder is such as to ensure against any sudden inilection' or change of position of the doctor blade. Thus, the longitudinal edges of the ridges adjacent the junction lines my be rounded or otherwise formed.

We claim:

1. In intaglio printing machines, a longitudinally gapped printing cylinder and a gap plate or cover for bridging the longitudinal edges of the cylinder gap and closing the gap, the longitudinal edge portion of the gap plate at the forward junction, considered in the direction of rotation of the cylinder, being elevated above thesurface of the cylinder forward of the line of junction, and the longitudinal edge portion of the cylinder at the second line of junction being elevated above the surface of the gap plate or cover forward of the line of junction so that adjacent the lines of junction longitudinal ridges are presented to bear against the under side of a doctor blade applied to the cylinder to relieve the pressure of the blade on the surface over which it is travelling as it passes over the lines of junction.

2. In intaglio printing machines, a longitudinally gapped printing cylinder and a gap plate or cover for bridging the longitudinal edges of the cylinder gap and closing the gap, the longitudinal edge portion of the gap plate at the forward junction, considered in the direction of rotation of the cylinder, being elevated above the normal surface of the cylinder forward of the line of junction, and the longitudinal edge portion of the cylinder at 'the second line of junction being elevated above the surface of the gap plate or cover forward of the line of junction so that adjacent the lines of junction longitudinal ridges are presented to bear against the under side of a doctor blade applied to the cylinder to relieve the pressure of the blade on the surface over which it is travelling as it passes over the lines of junction.

3. In intaglio printing machines, a longitudinally gapped printing cylinder and a gap plate or cover for bridging the longitudinal edges of the cylinder gap and closing the gap, the longitudinal edge portion of the gap plate at the forward junction, considered in the direction of rotation of the cylinder, being elevated above the surface of the cylinder forward of the line of junction, and the longitudinal edge portion of the gap plate or cover at the second line of junction being depressed below the normal surface of the cylinder to the rear of the line of junction so that adjacent the lines of junction longitudinal ridges are presented to bear against the under side of a doctor blade applied to the cylinder to relieve the pressure of the blade on the surface over which it is travelling as it passes over the lines of junction.

4;.- In intaglio printing machines, a longitudinally gapped printing cylinder and a gap plate or cover for bridging the longitudinal edges of the cylinder gap and closing the gap, the longitudinal edge portion of the gap plate at the forward junction, considered in the direction of rotation of the cylinder, being elevated above the normal surface of the cylinder forward of the line of junction, and the longitudinal edge portion of the gap plate or cover at the second line of junction being depressed below the normal surface of the cylinder to the rear of the line of junction so that adjacent the lines of junction longitudinal ridges are presented to bear against the under side of a doctor blade applied to the cylinder to relieve the pressure of the blade on the surface over which it is travelling as it passes over the lines of junction.

5. In intaglio printing machines, a longitudi nally gapped printing cylinder and a gap plate or cover for bridging the longitudinal edges of the cylinder gap and closing the gap, the longitudinal edge portion of the cylinder at the forward junction, considered in the direction of rotation of the cylinder, being depressed below the surface of the gap plate rearward of the line of junction, and the longitudinal edge portion of the cylinder at the second line of junction being elevated above the surface of the gap plate or cover forward of the line of junction so that adjacent the lines of junction longitudinal ridges are presented to bear against the under side of a doctor blade applied to the cylinder to relieve the pressure of the blade on the surface over which it is travelling as it passes over the lines of junction.

6. In intaglio printing machines, a longitudinally gapped printing cylinder and a gap plate or cover for bridging the longitudinal edges of the cylinder gap and closing the gap, the longitudinal edge portion of the cylinder at the forward junction, considered in the direction of rotation of the cylinder, being depressed below the surface of the gap plate rearward of the line of junction, and the longitudinal edge portion of the gap plate or cover at the second line of junction being depressed below the normal surface of the cylinder to the rear of the line of junction so that adjacent the lines of junction longitudinal ridges are presented to bear against the under side of a doctor blade applied to the cylinder to relieve the pressure of the blade on the surface over which it is travelling as it passes over the lines of junction. i

7. In intaglio printing machines, a longitudinally gapped printing cylinder and a gap plate or cover bridging the longitudinal edges of the cylinder gap and closing the gap, the longitudinal edge portion of the gap plate, considered in the direction of rotation of the cylinder, being elevated above the surface of the cylinder for- Ward of the line of junction and having the longitudinal edge rounded off, and the longitudinal edge portion of the cylinder at the second line of junction being elevated above the surface of the gap plate or cover forward of the line of junction and having the longitudinal edge rounded off so that adjacent the lines of junction longitudinal ridges are presented to bear against the under side of a doctor blade applied to the cylinder to relieve the pressure of the blade on the surface over which it is travelling as it passes over the lines of junction.

ERNEST WILLIAM HAWARD. ALFRED TYRRELL HOPKINS. 

